Panic Disorder with or without agoraphobia (PDA) in adolescents is prevalent, chronic, and associated with substantial impairment, including avoidance of school, disruption of peer involvement and avoidance of autonomous activities. Perhaps for this reason, PDA is associated with more depression in adolescents compared to other anxiety disorders. Effective treatments for PDA exist in adults. In a study nearing completion at our center, we are demonstrating that a developmental adaptation of an empirically supported cognitive-behavioral treatment for PDA is effective compared to a wait-list control group. However, a rather high percentage of adolescents have refused to enter the trial due mostly to the length and timing of sessions (weekly sessions for three months of treatment). Families reported wanting more immediate relief from the significant impairment and disruption of everyday activities their adolescents were experiencing. Further, parents were not significantly involved in treatment despite their eagerness to be involved. Substantial evidence now exists that the inclusion of parents in the treatment of adolescent PDA might provide additional clinical benefit. Finally, a substantial integrated situational and interoceptive exposure component was not included in adolescents'treatment. The purpose of this application is to evaluate the efficacy and acceptability of a brief, developmentally tailored eight-day intensive treatment for PDA in adolescents referred to as adolescent panic control treatment with exposure (APE) relative to a waitlist control group and to explore the relative impact of involving parents directly in treatment. Ninety patients aged 12-17 will be randomly assigned to one of three conditions: intensive treatment including family members, intensive treatment without family members, or a waitlist control group. The specific goals of this project are: (1) to evaluate the efficacy of intensive APE for reducing symptoms of PDA in adolescents, (2) to assess long term durability of effects at 3, 6, and 12 months following treatment, (3) to assess the relative advantage of involving parents in treatment, (4) to assess the impact of treatment on impairment and quality of life of adolescents and their families, and (5) to analyze hypothesized mechanisms of change.